Marshal ingersoll



M. INGERSOLL.

- Surveying Instrument.

Patented Feb. 8, 1859.

UNITED STATES PATENT OFFICE.

MARSHAL INGERSOLL, OF GRAFTON, OHIO.

SURVEYING INSTRUMENT FOR- DETERMINING INACCESSIBLE HEIGHTS ANDDISTANCES.

Specification of Letters Patent No. 22,876, dated February 8, 1859.

To all whomit may concern:

Be it known that I, MARSHAL INonnsoLL, of Grafton, in the county ofLorain and State of Ohio, have invented new and useful Improvements inSurveying Instruments; and I do hereby declare that the following is afull and complete description of the construction and operation of thesame, reference being had to the accompanying drawings, making part ofthis specification.

The nature of my invention consists in such a construction andarrangement of devices, that the exact distance of an object may bedetermined from the point at which the observation is made, Without theproc ess of chaining, as is now usually practiced; and also ofdetermining by a similar means the altitude of objects, by simplyknowing their horizontal distance from the point of observation.

My improvement consists of two parts: namely, the instrument ofobservation, and the target, and these are used in connection with eachother, andare accompanied by a table of calculation, a reference towhich will give any distance or altitude required.

Figure 1, is a side view of the instrument of observation, that is, fortaking dis tances and altitudes. Fig. 2, is a view of the opposite sideof the same instrument. Fig. 3, is a top view of the same. Fig. 4, is afront end view, and Fig. 5, is a back end view. Fig. 6, is a frontviewof the target. Fig. 7, is a topview of the same.

Like letters refer to like parts.

The instrument is mounted upon a staff or tripod, represented at A, inFigs. 1, 2, 4 and Its attachment is by aball and socket, B or itsequivalent; A rectangular plate O is mounted horizontally above the balland socket joint. Near the center of this plate, and below the surface,is placed a spirit level I), lengthwise of the plate O. Another spiritlevel may be placed at right angles to this. By means of these, theplate O can be adjusted to a horizontal position. The graduated limb ofa compass, with a polaric needle, may be placed upon the plate O, andconcentric with the axis of the ball and socket. The spirit levels maybe both placed within the limb of the compass. A telescope may also bemounted above the compass limb, as is the case in a transit instrument.A slit sight E, Figs. 1, 2, 3 and 4, is mounted upon the front end ofthe plate C. If a telescope is used, the eye piece of the same occupiesthe same position. The telescope should be rigidly mounted upon or abovethe plate O and parallel thereto. Upon the end of the plate O, oppositeto the sight E, is placed a stationary hair sight F, Figs. 1, 2, 3 and5. A line drawn through the center of this, and the slit sight E, formsa line parallel with the edge of the plate The vertical slit in thesight E, and the vertical hair, in the sight F, should coincide inposition. An adjustable vertical hair sight G, is mounted upon slidingways H, placed transversely to the plate O, and a little forward of thesight F. The sights G and F are constructed in the manner shown indetached sect-ion G and F, the hairs having but one metallic support,and being attached to a projection as shown in the figure, F and G, theopen sides of the supports facing each other, so that the hair in thesight G can be made to occupy a position upon an exact line with thestationary slit sight E and stationary hair sight F, and to move towardthe lefthand, without obstruction to the vision from any interveningobject. Thus, when the eye is placed to the slit sight E, the hair-sightG can be adjusted, so that it will exactly coincide with the hair sightF and slit sight E, and the two can be separated by moving the sight Gtoward the left the smallest fraction of an inch, and to any extentbeyond, within the limits of the instrument.

The hair sight G, is moved upon the ways H, by means of a very finescrew I, Figs. 3 and 5, the head of which is flattened for convenienceof turning the same, with the thumb and finger, as seen at I Figs. 3, 4and 5, or it may have a common milled head, which will answer the samepurpose. Between the head of this screw and the plate G is placed anindex plate J, through the center of which passes the screw I. An indexfinger K, Fig. 1, is attached to the screw I. The index plate is dividedinto any number of divisions corresponding to the lead of the screw I;for example, if the screw requires to be turned once around to move theadjustable sight G, one sixtieth of an inch, then the screw thread has alead of of an inch, and the dial plate J should be divided into sixtyequal parts. A vernier scale is also placed at the base of theadjustable hair sight Gr, having the same scale as the index plate. Now,it follows that if the slit sight E and the hair sight F are placed justtwelve inches apart, and the hair sight G adjusted to one sixtieth (5 ofan inch, at the distance of twenty four inches a target should be spreadto the distance of two sixtieths of an inch, or double the distance ofthe base line F, G, and so on, at the ratio of the square of thedistance for any length observed. Now, by a simple mathematicalcalculation, or what is more convenient, by reference to tablespreviously calculated, and within the range of practical observation, bythe known divergence of the lines E F and E G, the exact distance of anyobject can be accurately determined.

In graduating the Vernier scale upon the sliding way H, so asto-compensate for the error consequent upon the sight Gr being in adifferent plane from the sight F, a line should be drawn from the centerof the sight F toward the left, and at right angles to a line extendingfrom E to F. The true scale should first be set off upon the line thusdrawn from the sight F, and the graduations upon the Vernier made bydrawing lines from each of these divisions to the center of the sight E,where it intersects the face of the plate G. The point where said linescut the vernier will read the corrected distance. Or this correction maybe avoided by such a construction and arrangement of the sight F as tobring it into the exact plane of the moving sight G, in which case theVernier would need no corrected scale. Accurate observations can thus bemade. For the purpose of accomplishing this object, I construct a targetshown in Figs. 6 and 7 which or its equivalent should be used. Thisconsists of a staff L, about four feet in length, at the top of which isplaced a horizontal scale M, which has upon its face divisionscorresponding to those upon the index plate J and the Vernier scale ofthe adjustable sight G.

Now in using this instrument the sight G is set at a definite and knowndistance from the sight F; the target bearer places the target at anydesired distance and adjusts the target N, by means of signals from theengineer, so that it will be in an exact range with the sights E and F;then the target 0 is in like manner adjusted upon the graduated scale Muntil it is upon a line with the sights E, G. If then the figure atwhich it stands upon the scale M is compared in the table ofcalculations, with the figure upon the index J, or the distance thesights F G are apart, the table will show the exact distance of thetarget from the instrument.

In taking altitudes, I provide a graduated scale, P, which is attachedin a vertical position to the plate 0, opposite to the index J. Astraight arm Q is attached to the plate C, at a point opposite the sightE, by a pin upon which it articulates. The free end of this arm is heldin contact with the scale P by a guard R and can be elevated above ordepressed below the plate C. Sights can be placed upon this arm, throughwhich an observation can be taken, or for long distances a telescope canbe mounted thereon. The distance of an elevation having been determined,and the arm Q adjusted to the elevation or depression required, thereading upon the scale P when compared with the prepared table, willgive the altitude of the object.

By placing two instruments side by side and about a foot from eachother, (or at any definite and calculated distance), but so varied inform that the sights G both adjust inward, a system of triangulation canbe established, and the distance of observed points accuratelydetermined, without the use of a target.

lVhat I claim as my invention and desire to secure by Letters Patent, is

1. The construction of a surveying instrument, for taking distances andaltitudes, upon the general principle set forth in the foregoingdescription and specification.

2. I claim especially, the arrangement of the three sights E, F, G, ortheir telescopic equivalents, one of which is adjustable upon a scale,by which means, and the adjustment of a target having the samehorizontal scale, the distance of any object within the range of visioncan be determined. In this claim, I do not intendto confine myself tothe precise arrangement herein set forth, but to use a telescope inwhich a similar adjustment of hair sights, (or filaments of silk) areprovided for upon a definite scale, as herein set forth. Neither do Iintend to confine myself to any particular scale, but to ado-pt adecimal scale, or any other that I may see fit.

3. I also claim especially a horizontal target, having marked upon it ascale corresponding to that of the accompanying instrument, which targetis to be used in connection therewith as herein described, the sameforming a part of my invention.

4. I further claim the scale of altitude in MARSHAL INGERSOLL.

lVitnesses I. BRAINERD, W. II.- BURRIDGE,

